Ever wonder what Smart Mailbox Folders are for? In Mail.app version 2.0.5, they don't seem to do much except let you collapse away a group of Smart Mailboxes. Selecting a Smart Mailbox Folder doesn't show you any email messages from the contained Smart Mailboxes. Yet it was not always so...

In a previous version of Mail, I was able to right-click on a Smart Mailbox Folder and go to "Edit Smart Mailbox...", and set up a rule that allowed for any message in the sub-mailboxes to be shown when the folder was selected. This "smart" Smart Mailbox Folder still works in version 2.0.5, but it is no longer possible to create them. However, I have discovered how to modify the SmartMailboxes.plist to allow this.

Find the Smart Mailbox Folder you just created -- they're in the order that they appear in Mail.app. Check the MailboxName attribute to make sure it's the right one.

Change the IMAPMailboxAttributes property for the Smart Mailbox Folder you just created from 18 to 16.

Save your plist and quit the editor.

Reopen Mail.app

You will notice that when you right-click the edited Smart Mailbox Folder, you can now choose "Edit Smart Mailbox...".

For example, assume a Smart Mailbox Folder named Work that contains two Smart Mailboxes, Clients and Coworkers. You set up the Clients Smart Mailbox to show emails from your clients, and the same for Coworkers. Then for the Work Smart Mailbox Folder that we created using the steps above, create this rule:

Contains messages which match [ANY] of the following conditions:

[Message is in Mailbox] [Clients]

[Message is in Mailbox] [Coworkers]

Then, whenever you click on your Work folder, whether it's expanded or collapsed, you will see all your messages from either clients or coworkers. Note that you can also do this by creating a normal Smart Mailbox (instead of a Smart Mailbox Folder) and changing the IMAPMailboxAttributes value from 17 to 16, which will allow you to put other Smart Mailboxes into it.

Great hint. I'm hoping that someone has a solution to a smart mailbox problem I have. Before switching to IMAP (actually before being swtiched to IMAP) I had filters that moved messages to appropriate folders. With IMAP I've had to change to COPYING them. (else they disappear from the server and I can't see them from other machines, etc...). I have a smart mailbox that consists of all unread mail. Obviously, it will often contain duplicates: an inbox message and the one copied to a folder. I want to be able to tell the difference. Simple, go to View and check the mailbox column. Works fine, EXCEPT it doesn't stick. Is there a way to make it stick?

Good question. I found it out because I had one like this already from a previous version of Mail.app. It took a lot of trial and error to figure out just what was different about the mailbox I already had. Why they took that feature out of the gui, I have no idea.